U.S. patent application number 14/612874 was filed with the patent office on 2015-08-06 for skiving tool.
The applicant listed for this patent is ECOROLL AG Werkzeugtechnik. Invention is credited to Karsten Roettger.
Application Number | 20150217353 14/612874 |
Document ID | / |
Family ID | 52394884 |
Filed Date | 2015-08-06 |
United States Patent
Application |
20150217353 |
Kind Code |
A1 |
Roettger; Karsten |
August 6, 2015 |
Skiving Tool
Abstract
A combined skiver and a smooth rolling tool with a skiver head
and behind this a smooth rolling head, wherein between the skiver
head and the rolling head an exclusive torque transmitting coupling
is located which restricts the allowable axis shaft offset and/or
the angular position of the axes of the rolling head and skiver
head, to which the rolling head is connected, characterized in that
the skiver head (2) is guided through a workpiece bore via a
hydrostatic guideway.
Inventors: |
Roettger; Karsten; (Celle,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ECOROLL AG Werkzeugtechnik |
Celle |
|
DE |
|
|
Family ID: |
52394884 |
Appl. No.: |
14/612874 |
Filed: |
February 3, 2015 |
Current U.S.
Class: |
407/1 ; 407/30;
407/56 |
Current CPC
Class: |
B21C 37/30 20130101;
B23B 2270/26 20130101; B23B 29/03489 20130101; B23B 2260/108
20130101; B23B 29/03492 20130101; B23D 77/04 20130101; Y10T 407/10
20150115; B23B 29/03457 20130101; B23B 41/12 20130101; B23B 29/0346
20130101; B23B 2220/40 20130101; B24B 39/023 20130101; Y10T
407/1952 20150115; Y10T 407/19 20150115 |
International
Class: |
B21C 37/30 20060101
B21C037/30; B23D 77/04 20060101 B23D077/04; B24B 39/02 20060101
B24B039/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 5, 2014 |
DE |
102014202104.9 |
Claims
1. A skiving tool with (a) a tool head, (b) at least one skiving
knife, (c) at least one counterforce generation element, by means
of which a counterforce (F.sub.g) to a passive force (F.sub.e)
acting on the skiving knife can be generated and (d) a knife holder
onto which the at least one skiving knife and the at least one
counterforce generation element are fixed, wherein (e) the knife
holder is mounted to the tool head such that it can be moved in the
radial direction relative to the tool head.
2. The skiving tool according to claim 1, further comprising a
torque transmitting device connecting the tool head and the knife
holder such that they are torque-resistant in at least one rotation
direction.
3. The skiving tool according to claim 1, wherein the counterforce
generation element comprises at least a second skiving knife.
4. The skiving tool according to claim 2 further comprising at
least a third skiving knife and/or at least one adjustment device
by means of which a diameter of a circumscribed circle (D), on
which the cutting edges of the skiving knives are located, is
infinitely variable.
5. The skiving tool according to claim 1 further comprising at
least one adjustment device by means of which a diameter of a
circumscribed circle (D), on which the cutting edges of the skiving
knives are located, is infinitely variable, wherein the at least
one adjustment device is designed such that the at least one
skiving knife can be moved in the radial direction relative to the
knife holder.
6. The skiving tool according to claim 1 further comprising at
least one adjustment device by means of which a diameter of a
circumscribed circle (D), on which the cutting edges of the skiving
knives are located, is infinitely variable, wherein the adjustment
device is configured with a motor such that the knife holder can be
elastically deformed by the motor in such a way that the diameter
of a circumscribed circle (D) changes.
7. The skiving tool according to claim 1 wherein said at least one
skiving knife includes a plurality of skiving knives, and further
comprising an activation device by means of which all skiving
knives can be collectively moved radially inwards.
8. The skiving tool according to claim 1 further comprising a
diameter determination device for determining the diameter of a
circumscribed circle (D).
9. The skiving tool according to claim 8 further comprising: at
least one adjustment device by means of which a diameter of a
circumscribed circle (D), on which the cutting edges of the skiving
knives are located, is infinitely variable, wherein the adjustment
device comprises a motor for electronically changing the diameter
of a circumscribed circle (D); and a position control that is
connected to the adjustment device and the diameter determination
device, wherein the position control is configured to automatically
adjust the diameter of a circumscribed circle (D) to a nominal
diameter that can be predefined.
10. The skiving tool according to claim 1 further comprising a
roller burnishing tool which is rigidly connected to the tool head,
and/or a boring head that is rigidly connected to the tool
head.
11. The skiving tool of claim 4 wherein the at least one adjustment
device includes a motor.
12. The skiving tool of claim 5 wherein the at least one skiving
knife includes solely one skiving knife.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a skiving tool with (a) a tool
head, (b) at least one skiving knife and (c) at least one
counterforce generation element, by means of which a counterforce
to a passive force acting on the skiving tool can be generated
during operation of the skiving tool.
BACKGROUND
[0002] Skiving tools of this sort are used particularly during the
production of hydraulic cylinders for skiving the inner sides of
pipes. Hydraulic cylinders must meet high requirements regarding
the deviation of their shape: on the one hand, a high dimensional
stability must be achieved, in particular a high dimensional
stability and a low circularity irregularity. Additionally, the
tool should follow errors in straightness of the pipe preform as
they occur, especially on drawn precision steel pipes. These errors
in straightness have a value of 1 to 2 millimetres per metre of
pipe length. Furthermore, high requirements are set regarding the
surface quality.
[0003] In order to meet these requirements with completed hydraulic
cylinders, cold-drawn pipes are generally used as blanks. However,
cold-drawn pipes are complex to produce. Therefore, an attempt is
made to replace these with hot-rolled pipes. However, hot-rolled
pipes do not achieve the same accuracy in shape.
[0004] A thread-cutting device is known from DE 198 45 948 A1 which
may comprise a skiving tool that is arranged on a skiving head such
that it can be moved radially. The disadvantage of this type of
tool is that hot-rolled pipes are not easily processed, or cannot
be processed at all.
[0005] Combined skiving and roller burnishing tools are known from
DE 26 44 292 C2 and EP 1 512 492 B1 upon which oscillating knives
are mounted onto a skiving knife, which can be moved axially
relative to the tool head. The disadvantage of this type of system
is the often low stiffness in the radial direction.
[0006] A skiving tool according to the preamble is known from DE 10
2009 040 592 A1 which comprises a roughing tool and a skiving tool,
which are separated from one another by a coupling that allows for
a radial misalignment. The disadvantage of this type of tool is
that hot-rolled pipes cannot be easily processed.
SUMMARY
[0007] The invention aims to achieve a high dimensional stability
and a consistent surface quality of the part in process, even if
the pipe preform has a low dimensional accuracy and significant
curvature.
[0008] The invention solves the problem by means of a skiving tool
according to the preamble that comprises a knife holder to which
the at least one skiving knife and the at least one counterforce
generation element are fixed, and which is mounted on the tool head
such that it can be moved in the radial direction relative to the
tool head.
[0009] In addition, the invention is advantageous because, in order
to achieve a higher quality of structural component, this advantage
does not require a considerably complex construction to be
achieved.
[0010] Within the scope of the present description, the term tool
head should be understood in particular to mean the structural
component or the section of the skiving tool that is guided onto
the inner surface of the part when the skiving tool is in use. The
tool head preferably cannot be bent. In particular, the tool head
is the structural component or the section which is arranged in
front of the skiving knife in the torque flow; in other words, the
tool head directly or indirectly transmits a torque to the skiving
knife.
[0011] The knife holder is preferably mounted on the tool head such
that it is tilt-resistant. In other words, the knife holder is
fixed such that it cannot execute any significant tilting movements
relative to the tool head, but rather only a movement in the radial
direction.
[0012] The term skiving knife should especially be understood to
mean the structural component of the skiving tool that cuts off the
chip when the skiving knife is in operation. The cutting edge is
arranged on the skiving knife: this refers to the section of the
skiving knife that comes into contact with the part during
processing and cuts off the chip.
[0013] It is possible, and a preferred embodiment shows, that the
skiving knife is designed as cutting edge attachment that can be
firmly connected to the knife holder. In this case, the skiving
knife in particular has a positive material connection, a friction
connection or a form-fitting connection with the knife holder.
Alternatively it is possible, and a preferred embodiment shows,
that the skiving knife is an integral component of the knife
holder. The cutting edge attachment is preferably made of coated or
non-coated carbide, cermet or cutting ceramic.
[0014] The feature that at least one skiving knife is fixed on the
knife holder should be understood in particular to mean that the
skiving knife is fixed on the knife holder such that a relative
movement between the cutting edge of the skiving knife and the
knife holder is prevented. However, it is possible, and according
to a preferred embodiment intended, that the skiving tool comprises
at least two skiving knives and that one of the skiving knives is
fixed on the knife holder such that its position relative to the
other skiving knife or knives can be amended. It is only crucial
that the skiving knives can be put in a position in which they are
all fixed relative to the knife holder such that a diameter of a
circumscribed circle remains constant, even during the influence of
temporally varying passive forces acting on the skiving knives.
[0015] The fact that the at least one skiving knife and the at
least one counterforce generation element are fixed to the knife
holder means that when a cutting edge of the skiving knife moves
radially inwards about an offset vector, i.e. along the
longitudinal axis of the skiving tool, the counterforce element
also moves about the same offset vector. If two, three or more
skiving knives are available--as is the case according to a
preferred embodiment--, all skiving knives that are fixed on the
knife holder move about the same offset vector.
[0016] The at least one skiving knife and/or the at least one
counterforce generation element are preferably fixed to the knife
holder by means of a form-fitting, frictional or positive material
connection.
[0017] The diameter of a circumscribed circle is the diameter of
the circle upon which the points of the skiving knife that generate
the contour are located. The diameter of the circumscribed circle
closely corresponds to the inner diameter of the cylinder that is
created by the skiving tool. Any possible discrepancies between the
inner diameter of the finished cylinder and the diameter of the
circumscribed circle may occur due to the spring-back of the
material directly behind the cutting edge of the skiving knife.
[0018] The counterforce generation element should be understood to
mean an element of the knife holder by means of which a
counterforce is generated during operation of the skiving tool,
which counteracts the passive force acting on the skiving tool.
[0019] The feature that the knife holder is mounted such that it
can be moved in the radial direction relative to the tool head
should be understood to mean that the knife holder can conduct a
predetermined deviation from a central position and a further
deviation is prevented. It is possible for the knife holder to be
fixed relative to the tool head by means of at least one spring
element. This has the advantage that, upon insertion of the skiving
tool into the opening of the pipe preform, damage of an entry point
in the pipe preform by a non-centrically rotating knife holder can
be avoided. Alternatively, the knife holder is mounted on the tool
head with bearing slackness. This means that no increasing force
with increasing deviation from the central position acts on the
knife holder.
[0020] The knife holder is preferably guided in the axial direction
relative to the tool head. In particular, the knife holder is
guided in the axial direction relative to the tool head. For
example, the knife holder is mounted on a knife head and the knife
head comprises a bearing guide or roller guide that prevents a
movement of the knife holder in the axial direction relative to the
knife head, but enables a movement in the radial direction.
[0021] According to a preferred embodiment, the counterforce
generation element comprises guide elements, especially guide
rails, that are in contact with the inner wall of the cylinder
during operation of the skiving tool, such that the tool head is
guided on to the inner wall of the cylinder. In this case, it may
also be said that the knife holder is mounted such that it can move
in the radial direction relative to the guide elements.
[0022] The skiving tool preferably comprises at least three skiving
knives, especially exactly three skiving knives or exactly six
skiving knives. The advantage of this type of skiving tool is that
a high surface quality can be achieved, even with blanks that are
not dimensionally stable. For example, if the blank has a
straightness error, the chip thickness is adjusted for each of the
skiving knives. As a result, various passive forces act on the
skiving knives. The resulting total force on the knife holder
pushes the skiving knife into a new position in which the chip
thicknesses and thereby the passive forces are similar to one
another. It is also possible that the skiving tool has two or more
knife holders. These knife holders are preferably arranged behind
one another along a longitudinal axis of the skiving tool.
[0023] With skiving tools according to the prior art, a frictional
force must first of all be overcome before the skiving knives are
able to reach their new position. Due to the transfer from sticking
to sliding, this results in an abrupt change in the position of the
skiving knives, which is damaging to the surface quality.
[0024] However, the skiving knives on this type of skiving tool are
fixed to the knife holder and mounted such that they can move in a
radial direction relative to the tool base. It is thus easier for
the skiving knives to change their position in the event of a
circularity irregularity. Jerky changes in position are avoided,
thereby enabling an increase in surface quality. The above
described mechanism also applies to the procedure in the event of
circularity irregularities.
[0025] An advantage of the invention is that a high surface quality
of the finished pipe inner surfaces can also be achieved when pipe
preforms with higher straightness errors--for example, more than
2.5 millimetres per metre of pipe length--are being used.
[0026] It is especially favourable if the skiving tool comprises a
torque transmitting device, the torque transmitting device
connecting the tool head and the knife holder such that they are
torque-resistant in at least one rotation direction. The torque
transmitting device may, for example, comprise or be made of an
Oldham coupling. Alternatively or additionally, the torque
transmission device may comprise a claw coupling.
[0027] According to a preferred embodiment, the counterforce
generation element comprises a second skiving knife. In this case,
it is possible, and a preferred embodiment shows, that the first
skiving knife and the at least second skiving knife are securely
fixed to one another, for examples by a positive material
connection. In particular, the first skiving knife and the at least
second skiving knife are joined together as a single piece, i.e.
free of joints. Pipe preforms with a small diameter can be
processed in this way.
[0028] According to a preferred embodiment, the skiving tool
comprises at least a third skiving knife. In this case it is
possible, and a preferred embodiment shows, that the second skiving
knife and the at least third skiving knife are securely connected
to one another, for example by a positive material connection. In
particular, the second skiving knife and the at least third skiving
knife are joined together as a single piece, i.e. free of joints.
In addition to this, it is possible, and a preferred embodiment
shows, that all three skiving knives are arranged on the knife
holder and are preferably connected by a positive material
connection or joined as a single piece.
[0029] If the second skiving knife and the at least third skiving
knife are securely connected to one another, it is favourable if
the first skiving knife is fixed on the knife holder so that its
radial position is infinitely variable, for example by means of a
screw drive and/or actuator, especially a piezo actuator. In this
case, the diameter of the circumscribed circle is infinitely
variable.
[0030] Alternatively or additionally, the skiving knife comprises
at least one adjustment device, in particular a motor, by means of
which a diameter of a circumscribed circle, on which the cutting
edges of the skiving knives are located, can be infinitely
adjusted. The adjustment device is preferably fixed to the knife
holder, thereby achieving an especially high adjustment accuracy.
For example, the motor comprises a screw drive, so that the
diameter of the circumscribed circle can be manually adjusted.
[0031] It is particularly favourable if the number of skiving
knives is an integral multiple of three. Three skiving knives are
especially favourable. In this case, it is sufficient, and
according to a preferred embodiment intended, that only one of the
skiving knives is arranged such that it can move relative to the
knife holder. In this case, the diameter of the circumscribed
circle can be easily adjusted by changing the position of only one
of the skiving knives relative to the knife holder and thus
relative to the two other skiving knives.
[0032] The adjustment device is preferably designed to
electronically alter the diameter of the circumscribed circle. In
other words, the adjustment device comprises an actuator that is
arranged such that the diameter of the circumscribed circle can be
altered by activating the actuator. It is then possible to process
the inner surface of the part, as the tool is inserted into the
part. At the end of processing, the diameter of the circumscribed
circle can be reduced by activating the actuator and the skiving
knife can be removed without any possibility of protruding skiving
knives damaging the finished inner surface.
[0033] It is especially favourable if the skiving knives are
arranged in equidistant angle cuts, which results in particularly
high surface qualities. If precisely one of the skiving knives is
arranged such that it can move relative to the knife holder, it is
sufficient for two further skiving knives to be symmetrically
arranged on a level in which the movement of the skiving knife
occurs and which is perpendicular to the level at which the skiving
knives rotate, i.e. the level parallel to the longitudinal axis of
the skiving tool.
[0034] According to a preferred embodiment, the adjustment device
is designed such that at least the first skiving knife can be moved
in the radial direction relative to the knife holder. However, it
is possible for the adjustment device to be designed for manual
adjustment and/or electronic adjustment. It should be noted that
the numbering of the skiving knives is arbitrary. In other words,
it is insignificant which of the skiving knives is perceived as the
first skiving knife.
[0035] Alternatively or additionally to this, the adjustment device
is designed such that the knife holder can be elastically deformed
by the actuator in such a way that the diameter of the
circumscribed circle changes. In particular, it is possible for the
adjustment device to have two or more actuators, one of which moves
one of the skiving knives in the radial direction and the other
actuator deforms the knife holder as a whole, thereby changing the
diameter of the circumscribed circle.
[0036] It is especially favourable if the adjustment device
comprises at least one piezo motor. It is possible, and according
to a preferred embodiment intended, that the piezo motor comprises
a stack of piezo elements. It is particularly favourable if the
actuator has a lifting of 500 .mu.m. Piezo actuators have the
advantage of a higher stiffness, meaning that they can absorb the
passive force acting on the skiving knife. In addition, it is
possible to measure the deviation of the piezo actuator by
calculating its electrical capacity.
[0037] The skiving tool preferably comprises an activation device
by means of which all skiving knives can be collectively moved
radially inwards. This activation device may comprise, for example,
a binary motor, especially a hydraulic motor. In other words, the
activation device can be put in an active state in which the
skiving knives are in a radially outer position, meaning that the
inner wall of the pipe can be skived, and in a deactivated state,
in which the skiving knives are radially retracted, so that the
tool can be withdrawn from the skived pipe without the skiving
knives damaging the inner surface.
[0038] According to a preferred embodiment, the skiving tool
comprises a diameter determination device for determining the
diameter of the circumscribed circle and/or the inner diameter of
the finished pipe. For example, the diameter determination device
comprises a tactile body that is preloaded on to the inner side of
the pipe, meaning that the inner diameter of the pipe can be
determined from the deviation of the tactile body.
[0039] If the skiving tool comprises a roller burnishing tool--as
is intended in a preferred embodiment --, the measuring location at
which the diameter determination device determines the inner
diameter, is preferably located behind the roller burnishing tool
in a feed direction.
[0040] For example, the diameter determination device comprises a
device that is designed to measure the electrical capacity of the
piezo actuator, if a piezo actuator makes up part of the adjustment
device. The deviation is determined from the electrical capacity of
the piezo actuator, and from this, the diameter of the
circumscribed circle is determined. This may be done, for example,
by calculating the dependence of the deviation from the electrical
capacity in preliminary tests and placing it in on a graph. The
deviation can then be determined from the measured electrical
capacity by interpolation of the graph.
[0041] Alternatively or additionally, the diameter determination
device comprises a gauge, for example a glass gauge, which is
arranged relative to the first skiving knife such that the position
of the skiving knife relative to the gauge can be read or
automatically read. The adjustment device thus preferably comprises
a screw, the turning of which can change the radial position of the
first skiving knife. The skiving knife or a skiving knife
accommodation moves past the gauge during a change in the radial
position of the skiving knife, meaning that the change in position
can be read. In particular, the gauge comprises a scale, the
skiving knife or its holder comprising a marker, especially a
second scale, which enables the position of the skiving knife
relative to the gauge to be determined using the two scales. For
example, the two scales are arranged in the same way as with a
vernier calliper.
[0042] If the adjustment device is designed to deform the knife
holder, the knife holder preferably has a notch or another material
weakness that opens during deformation. The diameter determination
device is then designed to measure the size of the recession, so as
to determine the diameter of the circumscribed circle.
[0043] According to a preferred embodiment, the skiving tool has a
position control that is connected to the adjustment device and the
diameter determination device, and is designed to automatically
adjust the diameter of the circumscribed circle to a nominal
diameter that can be predefined. This means that wear and tear of
the skiving knives does not lead to a reduction in the dimensional
stability of the finished cylinder.
[0044] According to a preferred embodiment, the skiving tool
comprises at least one spring, by means of which the knife holder
is preloaded to a central position. The term central position
should be understood to mean a position in which the mid-point of
the circumcircle lies on the longitudinal axis of the skiving tool,
or at least closer to the longitudinal axis than it would without
the spring.
[0045] The skiving tool preferably comprises a boring head that is
arranged in front of the skiving knives in the machining direction.
It is favourable if the boring head is securely connected to the
tool head, particularly in a way such that it can be detached: this
enables the processing of pipes with large errors in cylindrical
form and straightness.
DESCRIPTION OF THE DRAWINGS
[0046] In the following, the invention will be explained in more
detail with the aid of drawings. They show
[0047] FIG. 1 in the right partial image, a longitudinal cut
through a skiving tool according to the invention, and in the left
partial image, a cross-section along the line A-A,
[0048] FIG. 2 a torque transmitting device in the form of an Oldham
coupling that is part of the skiving tool according to FIG. 1,
[0049] FIG. 3 a schematic image of the function of a position
control of the skiving tool according to FIG. 1,
[0050] FIG. 4 a second embodiment of a skiving tool according to
the invention,
[0051] FIG. 5 a third embodiment of a skiving tool according to the
invention and
[0052] FIG. 6 a fourth embodiment of a skiving tool according to
the invention.
[0053] FIG. 7 depicts a three dimensional view of a skiving-roller
burnishing tool according to the invention.
DETAILED DESCRIPTION
[0054] In the right partial image of FIG. 1 a cross-section through
a skiving tool 10 according to invention is depicted in the form of
a combined skiving-roller burnishing tool that comprises a tool
head 1, which may also be described as a tool body. In the left
partial image, which depicts a cut along the line A-A, it is clear
that the skiving tool 10 comprises a skiving knife 6.1. During
operation of the skiving tool 10, a passive force F.sub.p acts on
the skiving knife 6.1. The skiving tool 10 also has a second
skiving knife 6.2 and a third skiving knife 6.3. Each skiving knife
6 (reference number without a numerical suffix refers to all
objects of the same type) has a cutting edge 5. In other words, the
skiving knife 6.1 has a cutting edge 5.1, the skiving knife 6.2 a
cutting edge 5.2, and the skiving knife 6.3 a cutting edge 5.3.
[0055] The skiving tool 10 comprises a first counterforce
generation element in the form of a guide rail 8.2 that generates a
counterforce F.sub.g to the passive force F.sub.p during operation.
In addition to this, the skiving knives 6.2 and 6.3 function as
counterforce generation elements which also contribute to the
generation of the passive force F.sub.p.
[0056] The skiving tool 10 comprises a torque transmitting device
11, which comprises an Oldham coupling 3 and a coupling hub 2 in
the present case. The coupling hub 2 is connected to the tool head
1 by a screw 13. The skiving tool 10 has a knife holder 4 that is
preferably disc-shaped and therefore can be referred to as a
skiving disc. The torque transmitting device 11 is coupled with the
knife holder 4 such that it is torque resistant. The skiving knives
6.1, 6.2, 6.3 are mounted on the knife holder.
[0057] The tool head 1 has a radial guide 14 that comprises a first
guide surface 15, which is situated on a guide collar, and a guide
flange 19. The guide flange 19 is fixed by means of at least one
screw 16. The radial guide 14 ensures that the knife holder 4 can
only move in the radial direction, i.e. perpendicular to a
longitudinal axis L.
[0058] The skiving tool 10 comprises an adjustment device 7 which
has a stack of piezo elements in the present case. In the
embodiment depicted in FIG. 1, the adjustment device 7 is arranged
such that it can move the cutting edge 5.1 of the knife 6.1
radially outwards and inwards. If the adjustment device 7 is
activated such that the cutting edge 5.1 is moved radially inwards,
the diameter of the circumscribed circle D increases. The diameter
of the circumscribed circle D is the diameter of the circumscribed
circle K, i.e. the clearly defined circle on which the edges of all
the cutting edges 5 of the skiving knives 6 are situated.
[0059] The left partial image in FIG. 1 shows that the knife holder
4 comprises three guide elements 8 in the form of a first guide
rail 8.1, a second guide rail 8.2 and a third guide rail 8.3. When
the skiving tool 10 is in use, these guide rails 8 are in contact
with an inner wall 9 of a part 18 to be processed. The first guide
element 8.1 is part of the counterforce generation element.
[0060] FIG. 2 shows a perspective view of the Oldham coupling 3. It
should be recognised that the Oldham coupling 3 comprises a first
rail-like elevation 31 that faces towards the knife holder 4.
Offset at an angle of between 70.degree. and 110.degree.--for
example a right angle--to this, the Oldham coupling 3 has a second
elevation 32 that faces away from the knife holder. The first
elevation 31 interlocks with a groove 42 in the knife holder 4. The
second elevation 32 interacts with a second groove 22 that is
arranged on the coupling hub 2. This creates a torque-resistant
connection between the tool head 1 and the knife holder 4.
[0061] FIG. 3 schematically depicts a position control 21. The
position control 21 refers to a device that is designed to adjust a
deviation of the adjustment device 7 to a predefined nominal
deviation, which corresponds to a predefined nominal diameter
D.sub.Soll for the diameter of the circumscribed circle. It should
be recognised that the position control 21 is electrically
connected to the adjustment device 7 on one side and a diameter
determination device 17 on the other.
[0062] In the present case, the diameter determination device 17 is
made up of an electronic circuit, which creates an alternating
current on the piezo elements of the adjustment device 7, reads and
measures the phase shift between voltage and current. From this, it
calculates the capacity of the piezo elements and in turn the
deviation of the adjustment device 7. The position control 21
registers this deviation and compares it with the nominal deviation
and/or calculates the diameter of the circumscribed circle from the
deviation and compares this with the nominal diameter D.sub.Soll.
Should the calculated actual value D deviate from the predefined
nominal value D.sub.Soll, the position control 21 controls the
adjustment device 7 such that the value |D-D.sub.Soll| of the
difference reduces, ideally to zero. The electrical energy is
transmitted to the electronic circuit, for example, via cable or
slide contacts, or wirelessly via induction.
[0063] FIG. 4 shows a second embodiment of a skiving tool 10
according to the invention where the guide elements 8.1, 8.2, 8.3
are mounted on the coupling hub 2 and the guide flange 19. In
addition to this, the guide elements 8 are each screwed on with a
guide rail support 28.1, 28.2 and 28.3 and a screw. The guide
elements 8 are thereby securely connected to the tool head 1. The
grooves 44.1, 44.2, 44.3 enable a movement of the knife holder 4
relative to the guide elements 8.
[0064] FIG. 5 depicts a third embodiment of a skiving tool 10
according to the invention whose knife holder 4 comprises a slit 23
which carries the knife holder 4 across its full radial extension.
The knife holder 4 comprises recesses 27 that are arranged such
that a flexibility in the knife holder 4 along one of the
deformations created by the adjustment device 7 is greater than
along a deformation in another direction. The adjustment device 7,
which comprises a piezo actuator in the present case, is arranged
such that it is able to increase and reduce the slit 23 by creating
an elastic deformation by spreading the knife holder 4. The larger
the slit 23, the greater the diameter of the circumscribed circle
D.
[0065] FIG. 6 depicts a further embodiment of the skiving tool 10
according to the invention where the adjustment device 7 acts on a
cone 24 in the axial direction. If the adjustment device 7 is
activated, it pushes the cone 24 against contact surfaces 26.1,
26.2, 26.3. The contact surfaces 26 are each arranged between two
recesses 27.1, 27.2, 27.3 in the knife holder 4. Should the cone 24
move axially, the pressure on the contact surfaces 26 increases,
causing the knife holder 4 to become deformed. The contact surfaces
26 are each arranged at the same angles as the skiving knives 6, so
that the skiving knives 6 are pushed radially outwards by this
deformation. By activating the adjustment device 7, the diameter of
the circumscribed circle D is increased.
[0066] FIG. 7 shows a perspective, to-scale view of a skiving tool
10 according to a further embodiment. The skiving tool 10 comprises
a roller burnishing tool 46 that is rigidly connected to the tool
head 1. The roller burnishing tool 46 has a plurality of rolling
elements 48.1, 48.2, . . . , which are guided into a cage 50 with
radial slackness. The cage 50 is mounted on the tool head 1 such
that it can be rotated in the circumferential direction.
[0067] The knife holder 4 is mounted on a knife head 52 such that
it can be radially moved. The knife head 52 comprises the guide
elements 8 and is rigidly connected to the tool head 1. It should
be recognised that the tool head 1 has guide parts 54, by means of
which it lies closely on a finished inner side of the pipe. The
tool head 1 is thus guided in a self-centering manner.
TABLE-US-00001 Reference list 1 Tool head 2 Coupling hub 3 Oldham
coupling 4 Knife holder 5 Cutting edge 6 Skiving knife 7 Adjustment
device, motor 8 Guide element 9 Inner wall 10 Skiving tool 11
Torque transmitting device 13 Screw 14 Radial guide 15 Guide
surface 16 Screw 17 Diameter determination device 19 Guide flange
21 Position control 22 Groove 23 Slit 24 Cone 26 Contact surface 27
Recess 28 Guide rail support 31 Elevation 32 Elevation 42 Groove 44
Groove 46 Roller burnishing tool 48 Rolling element 50 Cage 52
Knife head 54 Guide part L Longitudinal axis D Diameter of the
circumscribed circle K Circumscribed circle F.sub.p Passive force
F.sub.g Counterforce
* * * * *